There is currently an increasing demand for sugar worldwide. Losses in sugar that occur during refining represent a serious economic problem as well as result in a diminution of the available supply. Therefore, an improved process that minimizes losses of sugar due to processing and is straightforward to perform would constitute a significant advance in the art.
Typically, sugar juice is extracted from a plant source such as sugar cane or sugar beets by milling or by diffusion. The resulting juice is about 12-18 Brix (percent sugar by weight) in concentration. This raw juice usually contains a considerable amount of extraneous matter, such as fiber and particles from the cane, and dirt, that comes from the surface of the plant source. The coarser matter is removed by screening, and the finer matter is typically removed in a clarification process. In order to arrest sucrose inversion, i.e., hydrolysis of sucrose to glucose and fructose, the juice is treated with lime to raise its pH to 7.5, and heated to 100.degree. C. Other treatments may also include adding phosphoric or sulfuric acid, depending on the characteristics of the juice.
The settling or clarification step used to purify the sugar juice removes fine extraneous matter therefrom. The settling step generally involves adding a flocculant to the sugar juice to be purified. The flocculants are believed to function by adsorbing onto the surface of fine, particulate matter with minimal points of attachment, thereby forming a flocculant-particulate matter network. The network containing the particulate impurities is removed from the sugar juice by a physical separation process including settling, air flotation, filtration and the like, resulting in a purified form of sugar juice. Common flocculants that have been used in this regard are typically polymers, in particular, polyacrylamide/poly(acrylate) copolymers obtained by the copolymerization of acrylamide and sodium acrylate (see, for example, U.S. Pat. No. 4,138,539 to Landolt et al.; and Chemical Abstracts No. 99:71334s). However, when such polyacrylamide/poly(acrylate) copolymers are used as flocculants for sugar juice purification, the speed and efficiency of flocculation can be undesirably low.
In addition, flocculants comprising a mixture of a cationic melamine:formaldehyde acid colloid and an anionic polyacrylamide are known to be useful for purifying sugar liquor (U.S. Pat. No. 4,009,706 to Shaughnessey). However, because such flocculants are obtained from melamine and formaldehyde, both of which are suspected carcinogens, the manufacture and use of such flocculants is highly disfavored.
Accordingly, there is a clear need in the art for flocculants for the purification of sugar juice, which are both effective and non-toxic.
Citation or identification of any reference in Section 2 of this application shall not be construed as an admission that such reference is available as prior art to the present application.